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Where is a Sperm Whale’s Blow Hole?

Meditation: This is cheating because I already know due to an exhibit I saw several years ago. But f you asked me this 5 years ago, I would have said “On the back, same place the blow hole is for all other whales.” But that would be wrong. So instead of a true meditation, I will present the facts as I understand them from the exhibit I saw at the National Geographic Society.

The blow hole of a sperm whale is on the upper left front corner of its squarish head. Strange, but the really interesting part is why. The land-based ancestor of the sperm whale had the normal two nostrils on its snout for breathing. When it adapted to the water, the left nostril became the blow hole and migrated rather understandably in an upward direction, but remained on the left side. But the right nostril was somehow folded inward, so that it became an internal sphincter-like opening that could allow air through in short bursts, creating an internal sound (in much the same way as a fart is produced). This sound then reverberates through the front of the sperm whale’s head, the part filled with spermaceti or whale oil. This oil lens focuses the sound before it enters the water, allowing the whale to direct a burst of sound that is reflected back by objects in the water. The whale detects these echoes and forms images of the objects. So the “missing” nostril evolved into the sound generator for the sperm whale’s sonar system.

Fact: The sonar-producing system in a sperm whale is the loudest sound system in any animal. It is suspected (Observations of sperm whales are difficult and rare) that this system can also be used to stun prey. Theoretically, an entire school of fish could be stunned and then eaten at leisure. The sphincter-like organ I described that produces the clicks for the sonar is known as the “phonic lips” or “monkey lips”. The blowhole is on the upper left and is S-shaped when it is closed. All toothed whales have this same basic arrangement of phonic lips and spermaceti. But I know from observation that dolphins’ blowholes are symmetrical in position and round in shape, so it seems to me that a different evolutionary path may have been taken for these non-sperm toothed whales.